AGAR PLATE METHOD USING LACTOBACILLUS-PLANTARUM FOR BIOTIN DETERMINATION IN SERUM AND URINE

An improved agar plate method of biotin bioassay using Lactobacillus p lantarum ATCC 8014 and bromocresol purple was established to determine biotin levels in human serum and urine. Samples were treated with 4.5 N H2SO4 to liberate free biotin, autoclaved for Ih and neutralized by 4.5 N NaOH, then 10 mu l was added to wells in each plate. The biotin levels were measured in 190 serum and 59 urine samples, and the means were 2.7+/-0.53 ng/ml and 12.4+/-5.56 ng/mg of creatinine, respective ly. The intra-assay coefficient varience (CV) were 3.2 (n=20) and 1.3% (n=23), respectively. The recovery of biotin added (10 ng/ml) to seru m was 110.7%, and to urine was 99.6%. These findings suggest that this assay is sufficiently accurate and reproducible for routine use in th e clinical laboratory. The excretion of orally administered biotin was also demonstrated by the method.